combine — Element-wise Combination

combineSeries(a, b, func) and combineDataFrame(a, b, func) combine two objects element-wise using a caller-supplied binary function. The result index is the union of both indices; a fillValue (default null) is used when only one side has a value for a given label.

Interactive Demo

Code Examples

import { Series, DataFrame, combineSeries, combineDataFrame } from "tsb";

// ── Series ──────────────────────────────────────────────────────────────────
const a = new Series({ data: [1, 5, 3], index: [0, 1, 2] });
const b = new Series({ data: [10, 2, 30], index: [0, 1, 2] });

// Element-wise max
combineSeries(a, b, (x, y) => Math.max(x, y)).values; // [10, 5, 30]

// Union index with fillValue=0
const c = new Series({ data: [1, 2], index: ["x", "y"] });
const d = new Series({ data: [10, 30], index: ["x", "z"] });
combineSeries(c, d, (x, y) => (x ?? 0) + (y ?? 0), 0).values;
// x:11, y:2, z:30

// ── DataFrame ───────────────────────────────────────────────────────────────
const df1 = DataFrame.fromColumns({ a: [1, 5], b: [100, 200] });
const df2 = DataFrame.fromColumns({ a: [10, 2], c: [1000, 2000] });

// Shared column "a": element-wise min; unshared columns processed with fillValue
combineDataFrame(df1, df2, (p, q) => Math.min(p ?? Infinity, q ?? Infinity));

// overwrite: false — unshared columns preserved as-is
combineDataFrame(df1, df2, (p, q) => Math.min(p ?? Infinity, q ?? Infinity),
  { overwrite: false });